Delayed constraint HEADACHE!

[user_deleted]

I want to have an object constrained to another object, whose parent is animated. I need a time offset to the animation too, so it's actually constrained to where it was/will be.

try/picture this:

- Get a poly sphere.
- Get a locator(1), and make it a child of the Sphere, and move it to the left of the sphere.
- Keyframe some rotations and translations on the sphere.

I need to get the delayed position of this locator1 (via an expression), but as it's parent is animated, we need some way to get the WORLD coordinates...

- Get a locator(2)
- constrain it (point) to the position of the first locator1.

Now I can get the world coordinates of locator2, and make my delayed expression from there...
First without the delay:

delayedObject.translateX=getAttr locator2.translateX;
(same for y,z)

That works ok, now add the delay:
[b]
float $delay=5;
float $dTime = currentTime -q-$delay;

delayedObject.translateX=getAttr -time $dTime locator2.translateX;
(same for y,z)[/b]

Here the problem lies. Although delayedObject does exactly what is is supposed to, following locator2 with a 5 frame delay - but the SPHERE remains fixed!?!? As soon as you remove the "-time $dTime" from the expression, the Sphere once again performs its moves/rots.

Can anyone explain what is going on here, and how I can get around this problem? Or can someone suggest another way to make a delayed point constrain?

Thanks for listening!

Cybotic

[stevesayer]

I have no idea why the sphere is doing that.

But you may wish to explore this alternate workflow: instead of using the -time flag with the getAttr command, just store the position at each frame in an array. This way Maya doesn't have to recalculate the positions of everything for every frame, it just looks up a single variable.

So if your delay is going to be 5 frames, declare an array variable with 5 triple values (for X, Y, Z position). At each frame have the first locator store its current position in the first slot, and bump the other values down. Then have the second locator take its position from the last slot. This way, Maya doesn't have to scrub back and forth internally as it animates.

Make sense? --Hopefully, that will fix whatever weird voodoo problem your sphere is having, too...

Good luck!

-Steve

[user_deleted]

hmm... nice idea - wouldn't have thought of doing things that way within Maya. Reminds me of a snake game I wrote on the sinclair ZXspectrum a while back.... used strings instead of arrays but I'm digressing...

I'll give it a go , 'cause I need to have the position at various delays, and its a bit slow doing a bunch of gettAttr calls. It wouldnt hurt for me to make an array for all the frames, to save the time of bumping the values around..

cheers

Cybotic.

[ame]

Hello,

you can try using the frame chace node:

createNode frameChace;

and connect the attribute the you need to it, one of the the attribute is time and you can use it to create off sets.

Hope this help, sorry I do not have maya in front of me right now to give you a more accurate example.

Later,

-a

[user_deleted]

definately good to know about. cheers